Some chemical properties of isolated pea nucleoli

Isolated nuclei and nucleoli of ungerminated pea embryos have been analyzed chemically for their content of DNA, RNA, zinc, iron, phosphorus, and protein sulfhydryl groups. The values obtained cannot be considered to represent the whole of the living nucleolar body as an undetermined amount of material is extracted from nucleoli in the course of their isolation. Only negligible amounts of DNA have been found in the isolated nucleoli; most of the DNA released on disruption of nuclei appears in a fraction showing very few structures under the light microscope. RNA is more concentrated in the nucleolus than in the nucleus or cytoplasm, but since nucleolar protein is 6 per cent of nuclear and less than 1 per cent of cytoplasmic protein, the total amount of nucleolar RNA is comparatively small. None of the other components listed occurs in high concentration in either nucleus or nucleolus.     

Actinomycetes in lake muds: dormant spores or metabolically active mycelium?

Homogenization and ultrasonication experiments on samples of lake muds indicated that Micromonospora strains were present as a mixture of mycelium and spores. In contrast, strains of streptomycetes and nocardioforms appeared to be in the form of arthrospores or fragmentation spores respectively. Micromonospora strains originally isolated from lakes were able to grow in both native and enriched muds incubated in the laboratory. Numbers of streptomycetes and nocardioforms did not increase in these muds and are presumed to be relatively inactive in this habitat. We postulate that Micromonospora strains have an active role in the lacustrine environment as well as in soil.     

Mixed Inoculations with Effective and Ineffective Strains of Rhizobium leguminosarum

An ineffective Rhizobium leguminosarum strain capable of forming green nodules of similar size and number as normally effective strains was tested for its ability to compete with an effective strain in nodule formation on the pea. The ineffective strain was found to be more competitive and influenced the pattern of nodulation by the effective strain on the same root system. Nodules containing both strains were pink and able to reduce acetylene.     

BEYOND SUN,SAND, AND STITCHES: ASSIGNING RESPONSIBILITY FOR THE HARMS OF MEDICAL TOURISM

Medical tourism (MT) can be conceptualized as the intentional pursuit of non‐emergency surgical interventions by patients outside their nation of residence. Despite increasing popular interest in MT, the ethical issues associated with the practice have thus far been under‐examined. MT has been associated with a range of both positive and negative effects for medical tourists' home and host countries, and for the medical tourists themselves. Absent from previous explorations of MT is a clear argument of how responsibility for the harms of this practice should be assigned. This paper addresses this gap by describing both backward looking liability and forward looking political responsibility for stakeholders in MT. We use a political responsibility model to develop a decision‐making process for individual medical tourists and conclude that more information on the effects of MT must be developed to help patients engage in ethical MT.     

Wildlife and climate change: assessing the sensitivity of selected species to simulated doubling of atmospheric CO2

We explored, using computer simulations, the sensitivity of four mammal species (elk, Cervus canadensis ; white-tailed deer, Odocoileus virginianus ; Columbian ground squirrel, Spermophilus columbianus ; and chipmunk, Tamias striatus ) within the continental USA to the effect of anticipated levels of global climate change brought about by a doubling of atmospheric CO₂. Sensitivity to the direct effects of climate change were evaluated using a climate-space approach to delineate the range of thermal conditions tolerable by each species. Sensitivity to indirect effects were evaluated by quantifying the association of each species to the current vegetation distribution within the continental USA and using this association to assess whether wildlife species distributions might shift in response to vegetation shifts under climate change. Results indicate that altered thermal conditions alone should have little or no effect on the wildlife species' distributions as physiological tolerance to heat load would allow them to survive. Analyses of the effects of vegetation change indicate that deer and chipmunks should retain their current distributions and possibly expand westward in the USA. For Elk and ground squirrels, there is a possibility that their current distributions would shrink and there is little possibility that each species would spread to new regions. This work emphasizes that the distributions of the four mammalian species are likely to be influenced more by vegetation changes than by thermal conditions. Future efforts to understand the effects of global change on wildlife species should focus on animal–habitat and climate–vegetation linkages.